SUMMARY: Fixing Sun keyboards

Regarding the repair of Sun console keyboards which have keys that
do not work, the following types of helpful suggestions were
provided:

1.) Cleaning under the keys with compressed air blown in
from above the keyboard.
2.) Removing the back of the keyboard and cleaning the contacts
with a solvent (isopropyl alchohol, distilled water,
electronic parts cleaner) or even with more compressed
air.
3.) Trying the above cleaning by just prying off the keycap with
a pocket knife, or preferably, two bent paper clips.
4.) Closer inspection might reveal broken leads to the key. If so,
these can be found with a magnifying glass and/or ohmeter.
The leads can then be re-soldered together.
5.) In some cases, there is a hardware problem with the key. This
can be the "plunger" or a small plastic U shaped part which
can break or come loose. Inspect working keys by removing the
key cap as described above. Then repair the broken key by
comparing to a working key and, if necessary, swapping out
the plastic U part with a less needed key.

Most responses say that their method almost always works. Thanks to
all who responded: